The present invention relates to data storage systems, and more particularly, this invention relates to managing dimensional stability issues.
In magnetic storage systems, magnetic transducers read data from and write data onto magnetic recording media. Data is written on the magnetic recording media by moving a magnetic recording transducer to a position over the media where the data is to be stored. The magnetic recording transducer then generates a magnetic field, which encodes the data into the magnetic media. Data is read from the media by similarly positioning the magnetic read transducer and then sensing the magnetic field of the magnetic media. Read and write operations may be independently synchronized with the movement of the media to ensure that the data can be read from and written to the desired location on the media.
An important and continuing goal in the data storage industry is that of increasing the density of data stored on a medium. For tape storage systems, that goal has led to increasing the track and linear bit density on recording tape, and decreasing the thickness of the magnetic tape medium. However, the development of small footprint, higher performance tape drive systems has created various challenges ranging from the design of tape head assemblies for use in such systems to dealing with tape dimensional instability.
Tape drives write and read multiple data tracks simultaneously. It is critical that all data tracks are written in the correct locations for proper operation during subsequent readback. If the dimension of the head changes due to temperature or other causes, or if the transducers on the head are not positioned in the proper, design-specified locations due to fabrication variations, then data tracks will be written/read at incorrect locations. Likewise, if the media is not consistent in its dimensions, then the data tracks will move after writing and not be in the same location when the tape is read. In either case, successful read back of the data will be impaired.
In the past, the management of dimensional stability issues was done by tolerance control. Each component had limits on how much variation from design parameters was allowed. As track density increased, the allowable limits for variation were also decreased. However, to continue to increase track density to support high tape cartridge capacities, this method is no longer feasible, as components cannot be made at lower variation. Accordingly, the capacity growth of future tape storage schemes will be limited if new techniques for managing head and media dimensional stability are not developed.